Oligodeoxynucleotides of specific base sequence will be synthesized to provide examples of structural elements in DNA. The stability of perfect helices and of mismatched helices will be measured as a function of temperature, salt concentration and solvent polarity. The effect of covalently and noncovalently bound mutagens will be assessed. The structures of DNA-mutagen complexes will be determined using circular dichroism, temperature-jump kinetics, nuclear magnetic resonance and other physical properties.